Sidelink communication using fixed frame periods

Abstract

Methods, systems, and devices for wireless communications are described. A first user equipment (UE) may be configured with a timing of a frame structure for sidelink communications via a shared channel. The timing of the frame structure may correspond to a fixed frame period (FFP), and the first UE may initiate sidelink communications at the boundaries of the FFPs. The first UE may also support techniques for determining whether to initiate a channel access procedure to occupy a shared channel during a first FFP. In one example, the first UE may determine whether to initiate the channel access procedure to occupy the shared channel during the first FFP based on monitoring the shared channel during a second FFP for a sidelink transmission from a second UE. In another example, the first UE may receive an indication of whether to initiate the channel access procedure during the first FFP.

What is claimed is: 
     
         1 . An apparatus for wireless communication at a first user equipment (UE), comprising:
 a processor; and   memory coupled with the processor, wherein the memory comprises instructions executable by the processor to cause the apparatus to:
 identify sidelink data to transmit in a first frame period of a plurality of frame periods, the plurality of frame periods having fixed frame durations established for communication by the first UE via a shared channel; 
 determine whether to initiate a channel access procedure to occupy the shared channel for the first frame period; and 
 transmit the sidelink data based at least in part on the determining. 
   
     
     
         2 . The apparatus of  claim 1 , wherein the instructions are further executable by the processor to cause the apparatus to:
 monitor the shared channel during a second frame period of the plurality of frame periods for a sidelink transmission from a second UE, wherein determining whether to initiate the channel access procedure to occupy the shared channel during the first frame period is based at least in part on the monitoring.   
     
     
         3 . The apparatus of  claim 2 , wherein the instructions to determine whether to initiate the channel access procedure to occupy the shared channel during the first frame period are executable by the processor to cause the apparatus to:
 detect the sidelink transmission from the second UE based at least in part on the monitoring;   determine to share a channel occupancy time initiated by the second UE comprising the second frame period based at least in part on detecting the sidelink transmission; and   refrain from initiating the channel access procedure to occupy the shared channel during the first frame period based at least in part on determining to share the channel occupancy time initiated by the second UE.   
     
     
         4 . The apparatus of  claim 3 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, in the sidelink transmission, an indication that the sidelink transmission is from the second UE, wherein detecting the sidelink transmission from the second UE is based at least in part on receiving the indication.   
     
     
         5 . The apparatus of  claim 2 , wherein the instructions to determine whether to initiate the channel access procedure to occupy the shared channel during the first frame period are executable by the processor to cause the apparatus to:
 determine to initiate the channel access procedure to occupy the shared channel during the first frame period based at least in part on failing to detect the sidelink transmission from the second UE.   
     
     
         6 . The apparatus of  claim 2 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, from a network entity, the second UE, or a third UE, an indication of a configuration of the second frame period; and   identify a starting boundary of the second frame period based at least in part on receiving the indication of the configuration of the second frame period, wherein the monitoring for the sidelink transmission from the second UE is based at least in part on identifying the starting boundary of the second frame period.   
     
     
         7 . The apparatus of  claim 2 , wherein the sidelink transmission from the second UE comprises a data transmission or a sharing information transmission. 
     
     
         8 . The apparatus of  claim 1 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, in downlink control information from a network entity, an indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by a second UE.   
     
     
         9 . The apparatus of  claim 1 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, in a groupcast transmission from a second UE, an indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by a third UE.   
     
     
         10 . The apparatus of  claim 9 , wherein the groupcast transmission comprises a bitmap, and a bit or time indicator in the bitmap for the first UE indicates whether the first UE is to initiate the channel access procedure to occupy the shared channel during the first frame period or share the channel occupancy time initiated by the third UE. 
     
     
         11 . The apparatus of  claim 9 , wherein the groupcast transmission comprises a field comprising an identifier of the first UE and an indication of whether the first UE is to initiate the channel access procedure to occupy the shared channel during the first frame period or share the channel occupancy time initiated by the third UE. 
     
     
         12 . The apparatus of  claim 1 , wherein the instructions are further executable by the processor to cause the apparatus to:
 receive, in a unicast transmission from a second UE, an indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by the second UE.   
     
     
         13 . An apparatus for wireless communication at a wireless device, comprising:
 a processor; and   memory coupled with the processor, wherein the memory comprises instructions executable by the processor to cause the apparatus to:
 identify respective traffic patterns associated with a plurality of user equipments (UEs); 
 determine, based at least in part on the respective traffic patterns associated with the plurality of UEs, whether each UE of the plurality of UEs is to initiate a channel access procedure to occupy a shared channel during a first frame period of a plurality of frame periods, the plurality of frame periods having fixed frame durations established for communication with the plurality of UEs; and 
 transmit, to the each UE, an indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period based at least in part on the determining. 
   
     
     
         14 . The apparatus of  claim 13 , wherein the instructions to transmit the indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period are executable by the processor to cause the apparatus to:
 transmit, in downlink control information, the indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by another UE.   
     
     
         15 . The apparatus of  claim 13 , wherein the instructions to transmit the indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period are executable by the processor to cause the apparatus to:
 transmit, in a groupcast transmission, an indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by another UE.   
     
     
         16 . The apparatus of  claim 15 , wherein the groupcast transmission comprises a bitmap, and each bit in the bitmap indicates whether a corresponding UE is to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by another UE. 
     
     
         17 . The apparatus of  claim 15 , wherein the groupcast transmission comprises a bitmap, and a time indicator in the bitmap indicates whether a corresponding UE is to initiate the channel access procedure to occupy the shared channel during each of one or more frame periods including the first frame period or share channel occupancy times initiated by other UEs. 
     
     
         18 . The apparatus of  claim 15 , wherein the groupcast transmission comprises a field comprising an identifier of the each UE and an indication of whether the each UE is to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time with another UE. 
     
     
         19 . The apparatus of  claim 13 , wherein the instructions to transmit the indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period are executable by the processor to cause the apparatus to:
 transmit, to the each UE in a unicast transmission, an indication of whether to initiate the channel access procedure to occupy the shared channel during the first frame period or share a channel occupancy time initiated by another UE.   
     
     
         20 . An apparatus for wireless communication at a first user equipment (UE), comprising:
 a processor; and   memory coupled with the processor, wherein the memory comprises instructions executable by the processor to cause the apparatus to:
 identify, at the first UE, a configuration of a timing of a frame structure for sidelink communication via a shared channel, wherein the frame structure comprises a plurality of frame periods having a fixed frame duration; and 
 communicate during one or more of the plurality of frame periods of the frame structure in accordance with the configuration. 
   
     
     
         21 . The apparatus of  claim 20 , wherein the instructions to identify the configuration of the timing of the frame structure are executable by the processor to cause the apparatus to:
 receive, from a network entity or a second UE, an indication of the configuration of the timing of the frame structure.   
     
     
         22 . The apparatus of  claim 20 , wherein the configuration of the timing of the frame structure is preconfigured at the first UE. 
     
     
         23 . The apparatus of  claim 20 , wherein the instructions are further executable by the processor to cause the apparatus to:
 identify the configuration of the timing of the frame structure based at least in part on a traffic pattern at the first UE.   
     
     
         24 . An apparatus for wireless communication at a wireless device, comprising:
 a processor; and   memory coupled with the processor, wherein the memory comprises instructions executable by the processor to cause the apparatus to:
 identify, based at least in part on a traffic pattern associated with a first user equipment (UE), a timing of a frame structure for sidelink communication at the first UE via a shared channel, wherein the frame structure comprises a plurality of frame periods having a fixed frame duration; and 
 transmit, to the first UE, an indication of a configuration of the timing of the frame structure. 
   
     
     
         25 . The apparatus of  claim 24 , wherein the wireless device comprises a network entity, and the instructions are further executable by the processor to cause the apparatus to:
 determine the traffic pattern associated with the first UE based at least in part on sidelink communication scheduled at the first UE by the network entity.   
     
     
         26 . The apparatus of  claim 24 , wherein the wireless device comprises a second UE, and the instructions are further executable by the processor to cause the apparatus to:
 receive, from a network entity or from the first UE, an indication of the traffic pattern at the first UE.   
     
     
         27 . The apparatus of  claim 24 , wherein the wireless device comprises a second UE, and the second UE comprises an anchor UE that is preconfigured, configured via signaling from a network entity, or selected by one or more UEs including the first UE.